Browsing by Author "CONTRERAS, R"

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    BIS(DIPHENYLPHOSPHINO)METHANE AND ITS SULFIDE OR SELENIDE DERIVATIVES AS LIGANDS IN RUTHENIUM(II) AND RHODIUM(III) COMPLEXES - CRYSTAL-STRUCTURE OF [(ETA(6)C(6)ME(6))RU(ETA(3)(SPPH(2))(2)CH)]CLO4
    (1995) VALDERRAMA, M; CONTRERAS, R; BASCUNAN, M; ALEGRIA, S; BOYS, D
    Reaction of complexes [(eta(6)C(6)Me(6))RuCl2](2) and [(eta(5)C(5)Me(5))RhCl2](2) with the ligands L = Ph(2)PCH(2)PPh(2) (dppm) or Ph(2)PCH(2)P(Se)Ph(2) in benzene solutions led to neutral complexes with the general formula [(ring)MCl(2)(eta(1)L)]. The reactivity of the uncoordinated P atom of dppm has been studied. When the reaction was carried out in methanol solutions, cationic complexes, with the ligands acting in their bidentate form, were obtained. Similar cationic perchlorate complexes were prepared using acetone as solvent in the presence of sodium perchlorate, yielding [(ring)MCl(eta(2)L)]ClO4, where L = Ph(2)PCH(2)PPh(2), Ph(2)PCH(2)P(Se)Ph(2) or Ph(2)P(S)CH2P(S)Ph(2). The complex [(eta(6)C(6)Me(6))RuCl{eta(2)(SPPh)(2) CH2-S,S'}]ClO4 reacted with sodium hydride in tetrahydrofuran or thallium pyrazolate in dichloromethane solution by deprotonation of the coordinated bidentate ligand giving the complex [(eta(6)C(6)Me(6))Ru{eta(3)(SPPh(2))(2)CH-C,S,S'}]ClO4. The structure of this complex has been determined by single crystal X-ray diffraction methods. The complex contains a tridentate C,S,S'-bonded ligand occupying three coordination positions of a distorted octahedral ruthenium centre, with an eta(6)C(6)Me(6) group completing the coordination sphere.
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    CATIONIC HOMOBINUCLEAR AND HETEROBINUCLEAR RUTHENIUM(II)-RHODIUM(III) COMPLEXES WITH DIMETHYL PHOSPHONATE AND HALIDES AS BRIDGING LIGANDS
    (1995) VALDERRAMA, M; CONTRERAS, R; ACEVEDO, J
    The synthesis of new anionic complexes of formula [(ring)MX(2){PO(OMe)(2)}](-) is described; they have been used as tridentate X,X',O-tripod-like ligands for the preparation of bimetallic compounds [{(ring)M}(2)(mu-1)(2){mu-PO(OMe)(2)}](+) and [(eta(6)-MeC(6)H(4)Pr(1))Ru(mu-Cl)(2){mu-PO(OMe)(2)}Rh(eta(5)-C(5)Me(5))](+).
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    COST-BENEFIT-ANALYSIS FOR THE USE OF HAEMOPHILUS-INFLUENZAE TYPE-B CONJUGATE VACCINE IN SANTIAGO, CHILE
    (1993) LEVINE, OS; ORTIZ, E; CONTRERAS, R; LAGOS, R; VIAL, P; MISRAJI, A; FERRECCIO, C; ESPINOZA, C; ADLERSTEIN, L; HERRERA, P; CASAR, C
    Cost-benefit analyses can be integral to the evaluation of interventions in developing countries. The authors compare the potential benefits to the Chilean Ministry of Health, in terms of treatment costs averted, by prevention of Haemophilus influenzae type b (HIB) invasive disease, with the costs of adding HIB conjugate vaccine to the diphtheria-tetanus-pertussis (DTP) immunization routinely administered to infants. In their base-case model, over a 10-year period (1991-2000), vaccination against HIB will prevent 1,229 cases of HIB invasive disease, including 713 cases of meningitis, 107 of whom would suffer severe, long-term sequelae, and between 29 and 116 deaths. Assuming a cost of US$1 for a full three-dose regimen of vaccine, the benefit/cost ratio of 1.66, with a net discounted savings of over $403,225, illustrates that HIB vaccine can be cost-beneficial. Sensitivity analyses which alter each of the variables in the analysis indicate that if the true incidence of HIB disease is twice the published rate, then three doses of vaccine remains cost-beneficial at US$3.
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    PREPARATION AND PROPERTIES OF PALLADIUM(II) AND RHODIUM(I) COMPLEXES CONTAINING BIDENTATE PHOSPHINE SULFIDE AND SELENIDE LIGANDS
    (1993) CONTRERAS, R; VALDERRAMA, M; YANEZ, S
    The synthesis and properties of cationic complexes of general formula (ML2{CH2(Ph2PE)2)]BF4, where M = Pd(II) and Rh(II), L2 = eta3-MeC3H4, {P(O)(OR)2}2H (R = Me, Et), COD, (CO)2, (CO)PPh3 and E = S, Se are described. The methylene proton of the coordinated phosphine sulphide or selenide ligands react with strong bases as BuLi in n-hexane or NaH in THF, to give neutral complexes of the type [ML2{CH(Ph2PE)2)], where M = Pd(II), Rh(I); L2 = eta3-MeC3H4, COD and E = S, Se. The complexes have been characterized by elemental analyses, molar conductivities, i.r., H-1 n.m.r. and P-31{H-1} n.m.r. spectroscopy.
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    UNUSUALLY STABLE TRIMETHYLPLATINUM(IV) COMPLEXES WITH AN O3PTC3 COORDINATION SPHERE - THE CRYSTAL AND MOLECULAR-STRUCTURE OF (C5H5CO[P(O)(OET)2]3PTME3)
    (1988) NETTLE, A; VALDERRAMA, M; CONTRERAS, R; SCOTTI, M; PETERS, K; VONSCHNERING, HG; WERNER, H